Originally Posted by everwinter
You have decreased tire wear with the higher tire pressure. Lower tire pressure increases tire wear.
I've noticed a small change in braking time.
I inflate them to 39, because I like the firmer ride, better mpg (1 mpg better), & I'm trying to get my tires to at least 40k & possibly beyond. Also I like the decreased resistance. With tires at 34 it feels like when I biked around with a low tire & required much more effort. With increased tire pressure you sail along with much less overall effort.
34 is the minimum, so 39 is hardly excessive. I know many who inflate to 10 over, which would be 44 for the focus.
I agree that 39 is not excessive.
I inflate to 40 PSI. Many tires these days are rated to 51 PSI or more, and some people inflate even higher (but i would not recommend it).
I average over 36 MPG in what I would call suburban/country commuting.
I also usually shift below 2000 RPM, since the car has good low end torque.